Réponses

2013-11-09T15:12:07+01:00
1) x=-9
(x-5)(3x-4)-(x-5)(x-9)
(-9-5)(3(-9)-4)-(-9-5)(-9-9)
(-14)(-27-4)-(-14)(-18)
(-14)(-31)-(-14)(-18)
434-252=182
2) (x-5)(3x-4)-(x-5)(x-9)
3x²-4x-15x+20-(x²-9x-5x+45)
3x²-4x-15x+20-x²+9x+5x-45
2x²-5x-25
3) (x-5)(3x-4)-(x-5)(x-9)
(x-5)(3x-4-x+9)
(x-5)(2x+5)